import json
import os

from PIL import Image
from torch.utils.data import Dataset
from torchvision.datasets.utils import download_url


class nocaps_eval(Dataset):
    def __init__(self, transform, image_root, ann_root, split):
        urls = {'val': 'https://storage.googleapis.com/sfr-vision-language-research/datasets/nocaps_val.json',
                'test': 'https://storage.googleapis.com/sfr-vision-language-research/datasets/nocaps_test.json'}
        filenames = {'val': 'nocaps_val.json', 'test': 'nocaps_test.json'}

        download_url(urls[split], ann_root)

        self.annotation = json.load(open(os.path.join(ann_root, filenames[split]), 'r'))
        self.transform = transform
        self.image_root = image_root

    def __len__(self):
        return len(self.annotation)

    def __getitem__(self, index):
        ann = self.annotation[index]

        image_path = os.path.join(self.image_root, ann['image'])
        image = Image.open(image_path).convert('RGB')
        image = self.transform(image)

        return image, int(ann['img_id'])
